This invention lies in the field of magnetic tape recording and playback systems. More particularly, it concerns tape decks which have both parallel wall vacuum columns and tapered wall vacuum columns. Still more particularly, this invention concerns means for restricting the amplitude of movement of the tape in the tapered vacuum columns.
Magnetic tape drives utilize constant width vacuum columns to maintain constant tension in the tape as it passes across the read/write head. In recent years tape drives have also used smaller tapered vacuum columns, or acceleration pockets, between the main constant width columns and the read/write head. These tapered columns decrease the mass of tape which must be rapidly accelerated by the tape driver, or capstan. The tape loop in the tapered column seeks its own position based upon pressure differential across the tape, and tape tension, friction, and dynamic acceleration forces. Thus, during acceleration of the tape drive the tape loops in the tapered columns constantly move inward and outward seeking a force balance. The distance the loop moves from maximum inward position to maximum outward position is called the tape loop excursion. During certain operating conditions such as start-stop, forward, reverse, or by-directional movements, the loop excursion can be excessive at certain resonant frequencies. This invention deals with a means to decrease this excessive loop excursion.